The invention relates to connecting devices and, more particularly, to heat recoverable connecting devices having cantilevered arms.
Connecting devices are necessary in making terminations and connections for electronic packages such as pin grid array packages (PGAP). Current electronic packages often include sixty-four or more pins. The pins may be inserted into sockets in a printed wiring board (PWB) or printed circuit boards (PCB) and then wave soldered for connection therewith.
Prospective users of such boards are concerned that it will be difficult to remove such electronic packages from the board because of the increasing number of pins which are being used. There is a certain amount of force required to insert and remove a pin from a standard socket. With the high count of pins on current electronic packages, the insertion and removal forces can be quite high. In fact, the number of pins may be so great that the electronic package itself may become damaged during insertion or removal. In order to avoid damaging the electronic package, it is desirable to have pins which can be attached or removed from sockets with low or zero force.
There are zero insertion force connectors currently available, e.g. the connector disclosed in OTTE et al, U.S. Pat. No. 3,740,839 (hereinafter Otte et al). The Otte et al connector discloses a ring which is made from material capable of reversing between austenitic and martensitic states and a second member encircled by the ring. The second member deforms the ring when the ring is in its martensitic state and is deformed by the ring when the ring is in its austenitic state. The ring increases and decreases in diameter for releasing or engaging a substrate inserted within the second member. A more detailed description of the above mentioned phenomena is found in U.S. Pat. Nos. Re. 29,904; 3,740,839; and 4,022,519 all of which are incorporated herein by reference.
The instant invention is an improvement over the above described connectors in that it eliminates the ring construction and it's inherent tolerance and manufacturing problems. The instant cantilevered arms are constructed to provide an effective connector having a large range of movement for pin accomodation. It can be appreciated that such an arrangement requires fairly sophisticated manufacturing techniques and that the components must be made within narrow tolerance limits.